Fuchsone dyes in a direct positive photographic process



Patented Dec. 6, 1949 UNITED srA'rEs PATENT OilFICE 2,490,758 4 s t FUCHSON E DYES IN A DIRECT POSITIVE iPHOTOGRAPHIC PROCESS Robert Eliot Stauffer and John Sponge, ester, N. Y., assighors to EastmanKodak CUE pany, Rochester, N. Y., a corp'oiation of New Jersey No Drawing. Application August 28, 1Q,

' Serial No, 46,714

I 6 Claims. (Cl. 95-88) This invention relates to photograph-y and parpropose to use forlthss purpose are hydroxy derivticularly to .a method or making direct positive atives of fuchsone oi fuc'hsoiiie-imonium dyes.

photographs. i I p w The structureioi-itiehsoneistasifollowsz Direct positive eiiects imayzbe ,produced by solarizing the developable latent image by overexposure, by using a second exposure to obtain the Sabbatier or the Clayden efiect or by redeveloping a developed negative image. Solarizj able sensitized products require very intense ex- 9:0

posures to obtain the desired direct positive 10 photogiiaph. .The an is second exposure has obvious disadvantages from the point of view of practical technique. Redevelopment adds at least two operations to the usual and normal developing procedum The hydroxy derivatives of fuchsone and the Fallesen U. s. applicationfser. No. 780,405, filed mgn dye a welle ognized October 17, 1947, describes forming a direct posiclasses of ye iflcexainples of compounds tive image in a suitable silverthalide emulsion by Whlch We flg fl'fis follbwsi exposing the emulsion intheusual way and dejf dji' r m of juchsone veloping it in a developer which is capable of 'giving aerial fog. The emulsion is preferably of the internal latent image 'typedsuch as described in E0 JG Davey and Knott U. "S. application Serial No.

790,232, filed December 6, 19 1'], now abandoned. @0

For practical use in the documentary photo- 1 1 Y graphic copy field, a direct positive print process @005 should possess certain features. The exposure required should be of the same order as that re- 99 w OH quired for ordinary contact silver halide paper, HOL

With a minimum of processing steps, it should yield a positive image haying clean whites and a O reflection maximum density on non-barytacoated stock of from -1.-1 to 1 .8 and should r 000B possess adequate contrast or gamma and sufil- Aunin tlimlboxy-neiqcid Schulz N0. 846

ciently short toe "in the characteristic curve to render line copy in a crisp, clean manner. In addition, for machine processing, it-is desirable to have the developing times for such material as short as can reasonably "be controlled, preferably less than 6-0 seconds. 40 We have found that the mate and eveness of development in the high density areas may be improved and in most cases, the minimum density may be lowered by processing a direct positive material of the type disclosed in Fallesen U. S. 5 application, Seria'l 1%. 780,405 in fol'hialdehydebisulflte-hydroq-ulnone nevelopersof type disclosed in Staufior 5; application 9%;569; illed: October 17., .1 947,-,.;and also icontainingacerbain tn phenyl methane :dyes. .Ihe meet a m methane dye constitutes the novel feature of the Present invention iii-iii the co p with sriseramsietais same-mete OaNa Light Green SFA Cone. Schulz No. 763

. HgN- =NH-HC1 NH, Aux-in tricarboxync acid 345 (Na salt) Pararosaniline Hydrochloride Schulz No. 779

. l, v .o v CH CH s :5 N .01 0Q, cm

NaOOC so l , NHCH$ I National Methyl Violet 2B cone. Schulz N0. 7 83 Erlochrome GeranolBlSchulz No.84!) s; N/CHa Fuchsone-imonium dues V C1 ""611, v CH: -03, NH, v c- VT z 40 I i Basic'Fuchsone RFN CH N(CH3)1 V N Crystal Violet Schulz No. 785 EtaN- N'Eta 0 i i /CH| 5 I i u N .0 1

H: Malachite reen ,7

' N/CH: SOa-%Ca Patent Blue W Extra Cone, Schulz No. 826

Xylene Cyanol FF extra. Schulz No. 828

The photographic emulsion used in the process of'our invention "is a gelatino silver halide emulsion such'as a silver bromide emulsion, a silver or; bromoiodide emulsion; or a-"silver chloroiodide emulsion. It need not contain optical sensitiz- Ammol Brilliant m 501ml, -n ing dyes, although certain sensitizing dyes'may 5. be added to it for the purpose of inducing aerial fog, as explained more fully in Fallesen application, Serial No. 780,405. A suitable emulsion is that known as Burtons emulsion, described in Wall, Photographic Emulsion, 1.92.9, pages 52 and 53. Burtons emulsion is made as follows:

A. Silver nitrate g 100 Water cc 500 Ammoniato form clear solution.

B. Potassium bromide g 80 Potassium iodide 1 g 50 Soft gelatin g 2.0 Water cc. 1000 C. Dry gelatin g 250 B is heated to 70 C. and A, cold, added to B with constant shaking, digested for 20 minutes at 50 C., and allowed to cool slowly. C is added after being allowed to swell for 20 minutes in water, drained, and melted. The emulsion is then set and washed.

An internal latent image emulsion, that is, one which forms the latent image mostly inside the silver halide grains, as described on pages 296 and 297 of Mees The Theory of the Photographic Process, 1942, is especially useful for the process of my invention.

Most of the internal latent image emulsions are silver bromo-iodide emulsions of high iodide content, preferably containing at least of iodide. Burtons emulsion is an emulsion of this type, having a silver iodide content of approximately of the content of silver halide. It is not absolutely essential, however, for the emulsion to contain silver iodide.

An internal latent image emulsion made as described in Davey and Knott U. S. application, Serial No. 790,232, filed December 6, 1947, now abandoned, may also he used according to my invention. This emulsion is prepared by first forming in the absence of ammonia and in one or more stages silver salt grains consisting .at least partly of a silver salt which is more soluble in water than silver bromide, subsequently converting the grains to silver bromide or silver bromoiodide, and if the silver iodide content of the emulsion is less than 6% calculated on the total silver halide, treating such grains with an iodine compound to bring the silver iodide up to at least 6%, ripening preferably in the absence of ammonia and then either washing out some of the soluble salts or washing out the whole of the soluble salts, followed by the addition of soluble salts such as soluble chloride or bromide. An example of an emulsion made in this way is as follows:

Solution No. 1

Inert gelatin grams 20 KCl do 20 at 40 C.

Water cc 560 Solution No. 2

KCl grams 100' 0 Water cc 520} at Solution No. 3

AgNOs grams 195 a Water cc 520 at 45 Solution No. 4

KBr grams 160 Ki d0 40 at 45 C.

Water cc 500 Run solutions Nos. 2 and 3 simultaneously into solution No. 1 in a vessel, taking seconds to do this. Then ripen for 1 minute at 45 C. Next add solution No. 4 then ripen for 20 minutes at 45 C. Next add 235 grams of inert gelatin (dry). Then ripen at 45 C. for 15 minutes during which time the gelatin dissolves. Set and shred the emulsion and then wash until free from all soluble bromide and then add about cc. of 10% solution of KCl (by weight), and then add water to make 3 litres.

An internal latent image type of silver halide emulsion may be defined as one which, when a test portion is exposed to a light intensity scale for a fixed time between 1/100 and 1 second, and developed for 4 minutes at 20 C. in the ordinary, surface developer (Example 1), exhibits a maximum density not greater than 1/5 the maxiimum density obtained when the same emulsion is equally exposed and developed for 3 minutes at 20 C. in an internal type developer (Example 2). Preferably the maximum density obtained with the surface developer is not greater than 1/10 the maximum density obtained when the same emulsion is developed in the internal type developer. Stated conversely, an internal latent image emulsion, when developed in an internal type developer (Example 2) exhibits a maximum density at least 5, and preferably at least 10, times the maximum density obtained when the same emulsion is exposed in the same way and developed in a surface developer (Example 1).

The developer used in the method of our invention should be one which produces oxidation fog or aerial fog. Such developers have been described by Dundon and Crabtree in American Photography, 1924, vol. 18, page 742. An example of such a developer is a hydroquinone developer containing little or no sulfite, and is illustrated in Example 3.

The aerial fog may be produced in the developer in various ways and may be accelerated or intensified by resorting to various expedients. The developer used should preferably have low sulfite ion content and should preferably contain no silver halide solvent more powerful (as a silver halide solvent) than sulfite. Aerial fog may also be increased by bubbling air vigorously through the developer in such manner that the air comes frequently into contact with the emulsion surface of the photograph during development. Certain chemical agents such as copper sulfate incorporated either in the developer or in the emulsion itself may be used to produce or encourage the production of aerial fog. Hydrogen peroxide or certain dyes such as methylene blue increase aerial fog. Fogging agents containing labile sulfur are, however, unsuitable. The fogging action should produce developable surface latent image in the unexposed silver halide grains as explained in the Fallesen patent application Serial No. 780,405.

The developers of Stauffer U. S. application Ser. No. 780,569 contain heterocyclic nitrogen containing ring compounds having 5 or .6 atoms in the heterocyclic rin and are so constituted as to increase the maximum density of the positive image obtained in developing solutions capable of producing aerial fog. Typical compounds used in such developers are benzotriazole, methyl benzo triazole, 5-nitroindazole and S-nitrobenzimidazole.'

In general, the hydroxy derivatives of fuchsone or the fuchsone-imonium dyes are used in these developers in amounts of from 0.0005 to 0.05 per Hydroxy derivatives of juchsone Dye Range Preferred Aurin 01-1 2-. 4 Phenolphthalcin .005- .04 .02 Eriochrome Azurol B .001- .05 Eriochrome Cyanine RC .00l .02 Aurin tricarboxylic acid (Na 5 .001- 1 Eriochrome Geranol R .00l .1

Fuchsone-zmomum dyes Dye Range Preferred Basic Fuchsin RFN .0005 Malachite green 0005-. 032 Methyl green 00005. 0064 Acro iol Brilliant Blue. .001 01 Light Green SFA Cone" .001 .05 Pararosanilinc Eydroehloride .001 02 National Methyl Violet 2B c0110.. 001 01 Crystal Violet .001 01 Patent Blue VS Extra Cone. 001 005 Xylene Oyanol FF extra 001 03 An ordinary "surface type developer, that is, one which develops an image only on the surface of the claims of internal latent image emulsions, is the following:

Example 1 p-Hydroxyphenylglycine grams Sodium carbonate (crystals) do 100 Water to liter 1 Development time, 4 min. at C.

An internal type developer, that is, one which develops an image inside the grains of an internal latent image emulsion is the following:

Example 2 Hydroquinone grams 15 Monomethyl-paminophenol sulfate do 15 Sodium sulfite (anhydrous) do 50 Potassium bromide do 10 Sodium hydroxide do Sodium thiosulfate (crystals) do 20 Water to liter 1 Development times, 3 min. at 20 G.

Our invention will now be described by reference to the following specific examples.

Example 3 An exposure onto a direct positive photographic paper having an emulsion such as the Davey and Knott emulsion described above was made on a 1:1 optical printer by exposing for seconds at I/ 11 and developing for 46 seconds in an open tray in a developer of the following composition:

Hydroquinone grams 30 Sodium sulfite (des.) do 50 Paraformaldehyde do 12.5 Sodium hydroxide do 6 Benzotriazole do. 2.5 Potassium bromide do 1 Basic Fuchsin RFN do 0.0005 Water to liter 1 This yielded a print of improved maximum density and lower minimum density than a similar exposure processed seconds in the same developer without the Basic Fuchsin RFN.

Example 4 A similar set of exposures to that of Example 3 was made on the same material by using additions of between 0.005 and 0.032 gram of Malachite Green per liter of developing solution.

This was found to increase print contrast.

Example 5 A sensitive material such as that used in Example 3 was exposed in the same manner as in Example 3 and developed for to seconds in the same developer by using 0.01 to 1. gram per liter of sodium salt of aurin. This gave better quality prints than similar material developed in the same solution for '75 seconds at F. without the dye in the developer.

Example 6 A similar set of exposures to that of Example 3 was made using from 0.00005 to 0.0064 gram of methyl green per liter of developer instead of Basic Fuchsin RFN. This was found to increase maximum density and decrease minimum density of the resulting image.

Example 7 was exposed in the same way and developed in a developer of the following composition:

Water to 1 liter.

Development of the exposed layer in this developer for times of and 120 seconds showed an increase in maximum density of the resulting image.

It will be understood that the compounds and examples included herein are illustrative only and that the appended claims are to be taken as a measure of the invention.

What we claim is:

1. The method of obtaining a direct positive image in a silver halide emulsion layer, which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsionlayer a test portion of which upon exposure to a light intensity scale for a fixed time between and 1 second and development for 3 min-j Water to 1 liter.

gives a maximum density at least 5 times the 4 minutes at 20 0.; in the following surtace developer (I):

Grams p-Hydioxyphenyl'g-lycine- 10 Sodium carbonate 100 -Waterto1 liter.

and developing the unexposed portion of said emulsion layer in a developing, solution which produces aerial fog, and containing a heterocyclic, nitrogen-containing ring compound.- hav.- ing at least 5 but not more than 6 atoms in the heterocyclic ring, and so constituted as: to increase the maximum density of the. positive image obtained in said developing solution which produces aerial fog, said developing solution also containing a small amount of a dye selected from the class consisting of hydroxy derivatives. of

fuchsone and fuchsone-imonium dyes.

2.v The method of obtaining a direct positive image in a silver halide emulsion layer, which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between /100 and 1 second and development for 3 minutes at C. in the following internal type developer:

Grams Hydroquinone 15 Monomethyl-p-aminophenol sulfate 15 Anhydrous sodium sulfite 50 Potassium bromide 10 Sodium hydroxide Sodium thiosulfate 20 Water to 1 liter.

gives a maximum density at least 5 times the maximum density obtained when the equally exposed silver halide emulsion is developed for 4 minutes at 20 C., in the following surface developer (I):

Grams p-Hydroxyphenylglycine 10 Sodium carbonate 100 Water to 1 liter.

and developing the unexposed portion of said emulsion layer in a developing solution which produces aerial fog, and containing a heterocyclic, nitrogen-containing ring compound having at least 5 but not more than 6 atoms in the heterocyclic ring, and so constituted as to increase the maximum density of the positive image obtained in said developing solution which produces aerial fog, said developing solution also containing a small amount of a hydroxy derivative of fuchsone.

3. The method of obtaining a direct positive image in a silver halide emulsion layer, which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between /100 and 1 second and development for 3 minutes at 20 C. in the following internal type developer:

Grams Hydroquinone 15 Monomethyl-p-aminophenol sulfate l5 Anhydrous sodium sulfite 50 Potassium bromide 10 Sodium hydroxide 25 Sodium thiosulfate 20 Water to 1 liter.

gives a maximum density at least 5. times the density obtained when the equally exposed silver halide emulsion. is developed for 4 Water/to miter... c and developing the unexposed portion of said emulsion layer in a developing solution which produces-1 aerial fog; and containing a heteroyclic, nitrogemcontaining ring compound having at last 5 but'not more than 6. atoms in the heterocycl-ic ring, and so constituted as to increase the maxhnum "density "or the-positive image'obtained in saiddeveloping solution which produc saetiarrog;said developing solution also containing a sinaliamo'iinti of fuehsone-iinonium dye.

- -,Tlhe. method oi obt inin directeositivs m e. in -si verw alideremwsion l yer. which comprises exposin tov light:- rays F to which the emulsion is sensitive, a. silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between and 1 second and development for 3 minutes at 20 C. in the following internal type developer:

Water to 1 liter.

Grams p-Hydroxyphenylglycine 10 Sodium carbonate 100 Water to 1 liter.

and developing the unexposed portion of said emulsion layer in a developing solution which produces aerial fog, and containing approximately 2.5 grams per liter of benzotriazole and also containing a small amount of a hydroxy derivative of fuchsone.

5. The method of obtaining a direct positive image in a silver halide emulsion layer, which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between /100 and 1 second and development for 3 minutes at 20 C. in the following internal type developer:

Water to 1 liter.

gives a maximum density at least 5 times the maximum density obtained when the equally exposed silver halide emulsion is developed for 4 11 minutes at 20 0., in th following surface developer (I) 4 Grams p-Hydroxyphenylglycine 1 Sodium carbonate 100 Water to 1 liter.

20 C. in the following internal type developer:

Grams Hydroquinone 15 Monometl yl-p-aminophenol sulfate 15 Anhydrous sodium sulfite 50 ys to which the Sodium thiosulfate 12 Potassium bromide 10 Sodium hydroxide 25 20 Water to 1 liter.

gives a maximum density at least 5 times the maximum density obtained when the equally exposed silver halide emulsion is developed for 4 minutes at 20 C., in the following surface developer (I):

Grams p-Hydroxyphenylglycine 10 Sodium carbonate 100 Water to 1 liter.

and developing the unexposed portion of said emulsion layer in a developing solution which produces aerial fog, and containing approximately 0.4 gram per liter of methyl benzotriazole and also containing a. small amount of a hydroxy derivative of fuchsone.

ROBERT ELIOT STAUFFER. JOHN SPENCE.

No references cited.

Certificate of Correction Patent No. 2,490,758 December 6, 1949 ROBERT ELIOT STAUFFER ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 3, line 59, next to last formula, right-hand portion thereof, after CH insert +ZnOl and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 18th day of April, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

